Mechanism for feeding strip material



Sept. 12, 1961 c. G. MAYER ETAL MECHANISM FOR FEEDING STRIP MATERIAL 8Sheets-Sheet 1 Filed June 15, 1958 FIG.1.

FIG-.6.

Sept. 12, 1961 c. G. MAYER ETAL MECHANISM FOR FEEDING STRIP MATERIAL 8Sheets-Sheet 2 Filed June 13, 1958 FIG.2.

ATTORNEY Se t. 12, 1961 c. e. MAYER ETAL 2,999,624

MECHANISM FOR FEEDING STRIP MATERIAL Filed June 15, 1958 8 Sheets-Sheet3 F l G 3 ATTORNEY Sept. 12, 1961 c. G. MAYER ETAL MECHANISM FOR FEEDINGSTRIP MATERIAL 8 Sheets-Sheet 4 Filed June 13, 1958 F'IG.5.

INVENTOR! ATTORNEY Sept. 12,1961 0. e. MAYER ET A]. 2,999,624

MECHANISM FOR FEEDING STRIP MATERIAL Filed June 13, 1958 I 8Sheets-Sheet 5 PIC-3.9.

ATTORNEY Se t. 12, 1961 c. G. MAYER ETAL 2,999,624

MECHANISM FOR FEEDING STRIP MATERIAL Filed June 13. 1958 8 Sheets-Sheet6 ATTORNE p 1 c. G. MAYER ETAL 2,999,624

MECHANISM FOR FEEDING STRIP MATERIAL Filed June 13, 1958 8 Sheets-Sheet7 FI G.12. FIG.14.

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INVENTORS Cae/Yez m5 Gem/4w 477/5: 5 Ja/rlYfiA-ITEWM K/zww ATTORNEYSept. 12, 1961 c. G. MAYER ET AL 2,999,624

MECHANISM FOR FEEDING STRIP MATERIAL Filed June 15, 1958 8 Sheets-Sheet8 INVENTOFU CZOEWil/l/J GMMM M575? aw/Iv flEifii/W K/Lzo B ATTORNEYUnited States Patent U 2,999,624 MECHANISM FOR FEEDING STRIP MATERIALCornelius Graham Mayer, Chobham, and John Bertram Killow, Betchworth,England, assignors, by mesne assignmcnts, to Radio Corporation ofAmerica, Princeton, NJ.

Filed June '13, 1958, Ser. No. 741,923 Claims priority, applicationGreat Britain June 18, 1957 9 Claims. (Cl. 226-50) This inventionrelates to mechanisms for feeding strip material in opposite directions,particularly for feeding film in cinematograph projectors.

It is often desirable to reverse the direction of film feed through acineinatograph projector; for example, when an initial length of filmhas been passed through the projector to ensure that the apparatus isfunctioning properly and it is desired to go back to the be inning ofthe film to begin the full length showing of the film. Moreover, where asound track is being recorded on the edge of a picture film, it issometimes necessary to feed the film backwards a little in order tobring the sound track into register with the picture film or for thepurpose of erasing and re-recording.

Such reverse movements of the film have to take place through the normalprojection gate between the driving sprockets, and are quite distinctfrom the reverse feeding which takes place outside the gate, after thefull length has been shown, for locating the beginning of the film atthe outer end of the coil so as to enable the film to be shown again. Ij I The problem of reversing the film becomes'difiicult in the case ofsound projectors because, while the film has to move in steps past thegate, it must move smoothly past the sound scanning device and is,therefore, arranged to pass over a drum associated with a flywheel. Whenreverse feed takes place, the film, instead of being drawn over the drumby a uniformly rotating sprocket may be drawn over the drum by means,such as claws, operating periodically on the film. Therefore, themaintenance of drum movement free from oscillations or jerks presents aproblem which it is one of the main objects of the present invention tosolve. Further objects of the invention are to ensure that the film, inthe reverse movement, is kept taut between the sound drum and thesprocket by which it is delivered to the sound drum, and that noabnormal accumulations of film occur anywhere along its track betweenthe spool from which it it is drawn and the spool by which it is takenup.

According to the invention, mechanism for feeding strip material inopposite directions between reversible rotary members, includes a rotorassembly which has a substantial inertial resistanceto acceleration andcomprises a drum or other rotor over which the strip passes intravelling between the rotary members, the rotor assembly being arrangedto be rotated freely by the strip material travelling thereover in onedirection, so as to smooth out fluctuations in the strip movement, andmeans other than the strip for driving the rotor assembly in the reversedirection at a speed such as to maintain tension in the strip betweenthe rotor and one of the rotary members. It is advantageous to constructthe rotor assembly so that it is not a simple flywheel but to constructit as a rotor with a separate flywheel. In the case of a cinematographprojector, as aforesaid, the rotary members are the sprockets and thedrum or other rotor is the sound drum. Preferably the drum is arrangedto drive the film by friction and friction means are provided fordriving the rotor assembly in the reverse direction. The friction drivemay comprise an intermediate rubber rimmed wheel movable to and from aposition in which it is frictionally driven by a driving wheel andfrictionally ice drives the rotor assembly. The diameters of theengaging surfaces of the driving wheel, intermediate wheel,

and rotor assembly may be such as to provide a double step-up gearing.Very conveniently the intermediate wheel is rotatably mounted on a slidearranged to be held in the driving position by a spring and positivelymoved away from such position, as well as permitted to move towards suchposition, by a manually actuated snapaction mechanism.

Advantageously, the circumferential speed of the drum is slightly higherthan the speed of the film, during the reverse feed, so as to maintaintension continuously between the drum and the sprocket by which the filmis delivered to the drum, in spite of fluctuating action due to claws orother means, such as an intermittently rotating sprocket. The dimensionsof the apparatus are such that the diameter of the sound drum must bequite small and it is therefore desirable to provide, as suggestedabove, a separate flywheel, but this may be fixed coaxially to the drum.

It has been found desirable to employ a pressure roller to act on thefilm passing over the sound drum and it is necessary to provide guidesfor the control of the film path laterally in passing forward over thedrum in order that the sound track on the film may be accurately alignedwith respect to means provided for scanning such sound track. In orderthat the film may feed backwards round the sound drum, all such guidanceon what then becomes the output side of the pressure roller has to beremoved in order that stable film motion is obtained. It is desirablethat the mechanical operation of removing such guides is carried out bythe same snap action mechanism which causes the friction drive to bealternately engaged and disengaged from the drum assembly.

It frequently happens that the film to be fed through the mechanism hasbeen cut and re-joined by means of a lap joint, or splice, whereby thethicknesses of the film is temporarily increased. For normal operationof the mechanism, such splices present no problem as the film is drawnforward around the sound drum by the action of the lower sprocket, andthe pressure roller lifts m0- mentarily to allow the splice to passbeneath it.

For reverse operation, however, the sound drum frictionally drives thefilm, and when a splice is fed backwards round the drum, the drumsurface driving the film would be required to provide such additionalforces as are required to lift the pressure roller in order that thesplice may pass beneath it. In practice it is found that such drivingforces cannot conveniently be provided within the dimensions ofcinematographs apparatus. The roller is, therefore, made from. a hardmaterial, such as nylon, with an anular channel, centrally disposedalong the length of the roller, filled with a ring of resilient materialsuch as rubber. The resilient ring is of greater diameter than theroller and therefore stands proud of it. The roller is associated with aspring which biases the roller downwards onto the drum and, under theaction of this spring, the resilient ring tends to flatten.

When feeding forward around the drum, therefore, the edges of the filmwhich normally carry the sound tracks are backed, where the film passesbeneath the roller, by the solid material of the flanges at the ends ofthe roller, and in practice, this is an important condition in order tobe able to secure satisfactory scanning and recording of certain typesof sound track.

When feeding backwards, the splice becomes gripped by the resilientcenter of the roller, particularly by virtue of the fact that theresilient material has a substantial are of contact with the drumbecause of the flattening referred to above. The resilient materialtherefore grips the splice before the splice reaches the pinch betweenthe drum and the hard flanges of the roller, and the resilient 3material thereby provides the additional traction required to lift theroller and allow the splice to pass beneath it.

Conveniently the apparatus is driven by a reversible electric motoracting through an endless flexible band, such as a belt, passing overdriving and driven elements, such as pulleys. The weight of the motormay be used to keep the belt taut, the motor being mounted on a hingedplatform. Spring means, acting on the platform, maybe provided foradjusting the belt tension and means may be provided for locking theplatform in a fixed position for transport.

I11 order that the invention may be clearly understood, apparatus inaccordance therewith will now be described in some detail, purely bywayof example, with reference to the drawings which accompany the presentspecification and in which:

FIGURE 1 is a rear elevation of an assembly of mechanism forming part ofa cinematograph apparatus;

FIGURE 2 is an elevation of the mechanism of FIG- URE 1 as viewed fromthe left-hand side thereof;

FIGURE 3 is an elevation of the mechanism of FIG- URE 1 as viewed fromthe right-hand side thereof;

FIGURE 4- is an elevation of part of the mechanism of FIGURES 1 to 3;

FIGURE 5 is a sectional side elevation of part of the mechanism ofFIGURES 1 to 3;

FIGURE 6 is a side elevation of a detail, shown partly in section;

FIGURE 7 is a plan of part of the mechanism of FIGURES 1 to 3.

FIGURE 8 is a side elevation of part of the mechanism of FIGURES 1 to 3.

FIGURE 9 is a perspective exterior view of the apparatus of which themechanism of FIGURES l to 8 forms a FIGURE 10 is a front elevation ofpart of the apparatus of FIGURE 9;

FIGURE 11 is a side elevation of the part appearing in FIGURE 10, asmall portion thereof being shown broken away to disclose the interior;

FIGURE 12 shows a portion of the mechanism appearing in FIGURES 2 and 4;7

FIGURE 13 is an end View of a portion of the apparatus of FIGURE 9;

FIGURE 14 is asectional side elevation of a detail appearing in FIGURE13; and

FIGURE 15 is a front elevation ofa further assembly of mechanism in thecinematograph apparatus.

In the normal operation of the apparatus, the film to be projected isdrawn off an upper spool S1 (FIGURE 9) by a sprocket 1, the film passingbetween a guiding shoe 2 and the sprocket 1 (FIGURE 3) which holds thefilm on the sprocket 1, to the gate past which it is drawn in knownfashion, by cam operated claws 2A (FIGURE 15) fixed to a plate 21}mounted to oscillate about an axis 2C and also to move at right anglesto its own plane under the action of two cams so as to cause the claws2A .to follow a path in the form of a closed loop as required. Theintermittently moving film then passes between guide flanges 3, 4(FIGURES 3 and 6), located either side of a skid 4A, to the pinchbetween a sound drum or rotor 5 and a pressure roller 6, the guideflanges 3, 4 being, during the forward feed of the film raised above tothe dotted line positions of FIGURES 3 and 6. They are lowered to thefull line positions by means described below. The roller 6 is mounted ona spindle 6C on an arm 6D pivoted about a fixed axis 6B. A spring 6A,acting on the arm 6D (FIGURE 7), presses the roller 6 towards the sounddrum 5. The roller 6 is of nylon and is formed with an annular-channelholding a rubber ring 6B for the purpose set forth above. The sound drum5 is fixed to a shaft 8 (FIGURE 5) mounted in bearings 9, 10, andcarrying a heavy flywheel 11, the inertia of which is such that theangular velocity of the sound drum 5 cannot fluctuate at the frequencyat which the film is fed by the claws or at any other frequency arisingin the machine, with the result that the fluctuating progress of thefilm is converted to smooth progress enabling the sound track to bescanned for the reproduction of the sound recorded thereon. Afterleaving the sound drum 5, the film passes over a pulley 5A to a sprocket12, driven at the same speed as the sprocket 1, the film being held onthe sprocket by a guiding shoe 12A. The film, after passing a guidingroller 13, is taken up by a spool S2 driven through a slipping clutch,in known manner, by pulleys and a helical spring belt 123. A similartake-up drive is provided for the upper spool and means are describedbelow for controlling the spools according to the direction of rotation.

When it is desired to reverse the motion of the film through themachine, a lever 14 fixed to a spindle 15, rotatable about a fixed axisand carrying a plate 16, is turned to the full-line position of FIGURE 3in which the plate 16 is located substantially as shown in FIG- URES 2and 12. The movement of this assembly, comprising the lever 14 and plate16, has a light snap action to-and-fro between positions in which a pin17 on the plate 16 engages either side of an open-mouthed slot 18 in acrank 16A. The plate 16 is held is each of these positions by a hairpinspring 19 anchored at its ends respectively to a fixed point and to apoint on the plate 16, and arranged to pass over a dead-center positionas the plate 16 passes from one of the said positions to the other. Whenthe plate 16 is moved from the position in which the pin 17 engages oneside of the slot 18 to the position in which it engages the other sideof the same slot 18, the pin 17 on the plate 16 knocks the crank 16A,pivoted about a fixed axis 16B, over a dead-center position, determinedby an arcuate spring anchored between a fixed point and the crank 16A,to the position shown in FIGURES 2, 4 and 12. The crank 16A controls thereverse movement of the drum 5 and flywheel 11, the spools S1 and S2, aswell as the position of the guide flanges 3, 4. The return movement ofthe crank 16A is etfected by knocking this back over the dead-centerposition when the plate 16 and pin 17 are returned across the slot 13.The lost motion between the plate 16 and the crank 16A enables themovements of the plate 16 to take place sharply, even though themovement of the crank 16A may be temporarily arrested as a result of thedelayed engagement of certain gears 48, 51 or 48A, 51 (described below)controlling the drive for the spools, such delay being due to teethmeeting end on. The leverage and impact exerted by the plate 16,moreover, assist in overcoming the comparatively strong reaction of thespring 16C, which exerts a substantially stronger moment than the spring19 and provides a quick action. The movement of the crank 16A in thecounter-clockwise direction is arrested by an adjustable stop 16E(FIGURES 2 and 12). When the plate 16 is in the position of FIGURES 2, 4and 12 against a second adjustable stop 16D, a bell-crank lever 20(FIGURES 2 and 4) pivoted about a fixed axis 21 and connected to theplate 16 by a link 22, permits a spring 23 to hold a reciprocable slide24 in a position such that the sound drum 5 is positively driven in thereverse direction to that in which it is driven by the film during thenormal projection operation. The speed of the drum in this reversedirection is about 4% greater than the speed in the normal direction soas to ensure that there is no bunching or accumulation of the filmbetween the sprocket l2 and the sound drum 5, particularly when thereverse drive begins.

The slide 24 is formed with two slots 25, 26 enabling itto reciprocateon two pins 27, 28 and, when it is in the position of FIGURE 2, anintermediate rubber wheel 29, rotatably mounted on the slide 24,transmits the drive from the rim 30a of a wheel 30 to the flywheel 11.The drive is by friction and the rubber wheel 29 has two rims 31, 32 ofdifferent diameters that respectively engage the wheel 30 and a rim 33on the flywheel 11, the wheel 30 being controlled by means describedbelow to rotate only during the reverse film feed. The diameters of theengaging rims is such that a double step-up gearing is provided. Whenthe lever 14 is turned to the position corresponding to the normaldirection of film movement so that the plate 16 knocks the crank 16Aback over the dead-center position to the position in which it engagesthe stop 16E, the link 22 turns the bell crank lever 20 to a positionsuch that a lug 34 on the bell crank 20 pushes on a lug 35 on the slide24 and moves it, against the actionof the spring 23, to a position inwhich the rubber wheel 29 is separated from the wheel 30 and theflywheel 11.

During the reverse movement of the film, the guide flanges 3, 4 areretracted to the positions shown by full lines in FIGURE 6. The reasonfor this is that it has been found that, with the guide flanges 3, 4continuously in the raised positions, the passage of the film over theskid 4A is unsatisfactory. This skid 4A (see FIGURE 6), which is notrotatable although it has a certain amount of play about its axis, has acertain amount of lateral play against a stiff helical Spring 37,together with the retractable guideflanges 3, 4, which can move with theskid 4A, either toward or away from the spring 37, under control of anut 37A screwed onto a spindle passing through the flanges 3, 4, theskid 4A and the spring 37. The movement is for the purpose of adjustingthe lateral position of the film path over the drums 5. By retractingthe guide flanges 3, 4 to below the surface of the skid 4A as shown inFIGURES 3 and 6, the film is free to follow a path out of the pinchbetween drum and roller 6 without any lateral restraint whatever. Theway in which the retraction of the guide flanges 3, 4, is effected willnow be described.

The bell crank lever 20 is connected by a link 38 to another bell crank39 rotatable about a fixed axis 40. The link 38 is coupled to the bellcrank 39 by a nipple 38A which is pivoted to the bell crank 39 and isadjustable along the link 38 so as to provide an adjustment to theangular location of bell crank 39 relative to bellcrank 20. An elongatedslot 41 in the bell crank 39'engages a pin 42 projecting from the rearof a slide 'plate 43. From the lower end ofthe slide'plate 43, a

pin 44 engagesthe rear guide flange 3 and also, through a bushing 45,the front guide flange 4, Spring loading of the rear guide flange 3against the skid 4A is obtained by the spring 37, and of guide flange 4against the skid 4A by a ,spring washer 45A, interposed between theflange 4 and a nut 378. Thus, the dimension between the faces of theguide flanges 3, 4 is automatically maintained equal to the length ofthe skid 4A, to thus provide accurate lateral guidance of the filmaround the sound drum 5 when the guide flanges are in their raisedpositions and when the film is fed in the forward direction forprojection.

When the bell crank lever 20 is moved to the position corresponding toreverse film feed, a corresponding movement is transmitted to hell crank39 by the link 38 and adjustable nipple 38A. The slot 41 therefore actson the pin 42 to move the slide plate 43 downwards, which in turnretracts the guide flanges 3, 4 to the positions of FIGURES 3 and 6(full lines) by causing movement of the pin Y44 and bushing 45.Conversely, when the bell crank lever 20 is returned to a positioncorresponding to normal direction of film feed, the guide flanges 3, 4are pushed upwards by pin 44 and bushing 45 so that they stand proud ofskid 4A, and firmly spring loaded inwards towards each other, againstthe ends of the skid 4A by the action of spring 37 and spring washer45A. A tension spring 42A (FIGURE 4) is connected between the pin 42 anda fixed point to eliminate backlash in the motion of the pin 42.

The wheel 30 by which the sound drum is driven in the reverse directionis continuously geared during the reverse feed to the electric motor 53that drives the machine. This motor is a reversible motor so that thedirection in which it rotates is controlled by switch means. Clearly, itis undesirable for the motor to be started in one direction when thesound drum drive mechanism is set for the opposite direction. Therefore,a switch 46 under the control of the slide 24, is provided forpreventing the motor 53 from being started in the wrong direction. Afinger 47 on the slide 24 is moved to open the switch 46 when thepositive drive to the sound drum is disconnected. This may be arrangedto control the motor circuits in a number of ways that will be clear tothose skilled in the art. For example, it may be arranged to ensure thatthe circuit for starting the motor in the reverse direction cannot beclosed. Closure of the switch 46 may operate a relay for ensuring thatthe motor cannot start in the forward direction when the drive for theflywheel 11 is connected.

The motor 53 is arranged to drive the machine through a belt 74 (FIGURE15) that embraces a pulley wheel 73 on the motor 53 and a pulley wheel75 mounted to drive a spindle 75A (FIGURE 2). In actual fact, each ofthese pulley wheels has two belt surfaces of different diameters joinedby a conical surface, and a belt shifting mechanism (not shown) isprovided so that there is a two-speed drive in which the belt eitherembraces the larger diameter on one pulley and the smaller diameter onthe other, or the smaller diameter on the first and the larger on thesecond. Either of these two speeds can be selected both for forward orreverse running.

The spindle 75A drives a worm 75B which meshes with a skew gear 75C fordriving the sprocket 12 and with a skew gear 76 which, through a skewgear 51, drives a further skew gear 51A connected to the uppersprocket 1. Thus, when the motor is reversed, the sprockets 1 and 12 arereversed as is required.

The gearing for respectively driving the spools S2, S1 comprises skewgear wheels 48, 48A mounted respectively to rotate about axes 50, 55 onthe crank 16A (FIG- URES 8 and 12). Pulley wheels 49, 52 are fixedrespectively to the gear wheels 48, 48A. The wheel 30 by which theflywheel 11 is driven is also fixed coaxially to the gear wheel 48A.When the crank 16A is in the position for reverse running, the gearwheel 48A meshes with the skew gear 51 so that a pulley wheel 54 (FIGURE10) is driven, through the medium of a spring belt by the pulley wheel52, to rotate the upper spool S1 through a friction clutch describedbelow. When the crank 16A is in position for forward drive, the gear 48Ais withdrawn from the gear 51, but the gear 48 is in mesh therewith, sothat the pulley wheel 49 is rotated to drive the lower spool S2 throughthe belt 12B. Referring to FIGURES 10 and 11, it will be seen that thespool S1 is fixed on a spindle 55A mounted in ball bearings 56 in acasing 57 pivoted about a fixed axis 58 to a lateral protuberance on anarm 59 that is fixed to the main body of the projector so as to extendvertically upwards therefrom. Beyond the ball bearings 56, the spindleSSAcarries a drum 60 encircled by a ring 61 of friction material. Thislies inside a cup 62 fixed coaxially to a horizontal spindle rotatablein a bushing 63 on the arm 59 and carrying the pulley wheel 54. The axisof the spindle 55 is very slightly below the axis of the cup 62. A smallfinger operated lever 64 is pivoted about a fixed axis 65 on the arm 59,and a cable 66, incorporating a tension spring 67, extends between apoint 68 on the lever 64 and a point 69 on the casing 57.

When the finger lever 64 is in the full line position of FIGURE 11,there is substantially no tension in the cable 66, so that the drum 60and friction ring 61 are maintained in frictional engagement with thecup 62 only by the weight of the spool and of the film thereon. This issufficient and satisfactory for the purpose of reversing the filmmotion, when the film is threaded over sprockets 1, 12 in the normalmanner, because the speed of the film is restricted by the rate ofrotation of the sprockets and there is considerable slip between thering 61 and the cup 62, although'thetractive effort increases as thefilm builds up on the spool S1, thus increasing the weight and friction.

However, when it is desired to rewind the film speedily and directlybetween spools S2, S1, as it is the case when the film has completed itspassage through the machine from spool S1 to S2, it is desirable toaugment the friction dueto gravity, especially when large diameterspools containing considerable lengths of film and having greaterinertia are in use. For this purpose, the finger lever 64 may be movedover to the chain line position of FIG. 11. By this means, the slipbetween the ring 61 and the cup 62 is reduced, the tractive effect onthe spool S1 is increased, and a faster rewind speed is obtained. Then,the assembly comprising the cable 66 and spring 67 is stretched due tothe extension of the tension spring 67, and the corresponding increasedtension causes the casing 57 to tend to turn about the axis 53, therebyincreasing the frictional engagement between the ring 61 and theinterior of the cup 62.

When the finger lever 64 is in the full line position (FIGURE 11), itbears against a stop 70, and when it is in the chain line position, itbears against a stop 71. To hold the lever 64 in each of thesepositions, a tension spring 72 is connected between a fixed point 73Aand an eye 74A in the cable 66, between the spring 67 and the lever 64.When the finger lever 64 is moved in either direction between its twopositions, the spring 67 is first stretched and then relaxed, so that adead-center position is traversed.

As the drive has to be effected in opposite directions of rotation, ajockey pulley for the belt 74 is avoided and, instead, the motor 53 isfixed on a hinged platform 77 (FIGURE 13) so that the weight of themotor itself keeps the belt 74 taut in each direction of motor rotation,the hinge being at 78. Means are provided, however, for adjusting thebelt tension and for this purpose an apertured extension '79 is formedon the free edge of the platform 77 and a rod 39 passes freely throughthe aperture and is provided at its lower end with a peripheral flange81 which supports a helical compression spring 82 concentric with therod 80. The portion of the extension 79 around the aperture rests on thespring 82. Therefore, the moment of the weight of the motor about thehinge 78 of the platform 77 is balanced by the moment due to the belttension and the moment due to the spring 82. By varying the moment dueto the spring 82,, however, the belt tension can be varied. This iseffected by raising and lowering the rod 80 so as to turn the platformslightly about its hinge 78. Raising the rod 8f) takes a little tensionoff the belt and increases the load on the spring 82. The movement ofthe rod 80, therefore, has to be sufficient to accommodate the increasedcompression of the spring 82; as well as the slight raising of the motor'53. Lowering the rod 80 increases the tension in the belt 74 andcausesthe stress in the spring 82 to relax.

Means are provided also for locking the motor platform 77 againstmovement when it is required to transport the apparatus from place toplace. For this purpose, the top of the rod St) has pivoted thereto atwoarmed lever 83, one arm 34 of which being considerably longer thanthe other arm 85. When the apparatus is in the operative condition, thislever is in a horizontal position shown by full lines in FIGURE 13 andrests on the top of a bushing 86 through which the rod 80 passes. Thisbushing 86 is screwed into a support 87, and it is by turning thebushing 86 in its support 87 that the rod 80 can be raised and loweredfor adjusting the belt tension as aforesaid. The face 87A of the leverthat rests on the bushing 86 is slightly convex. Strictly speaking,however, this face is constituted by two convex edges, the cross-sectionof the lever being U-shaped as shown in FIGURE '14 and the top of therod 80 being pivoted between the two limbs of the U-shaped cross-sectionby means of a pin 88. By turning the long arm of the lever throughsubstantially a right angle, the end of the short arm is caused to reston the top of the bushing, as shown in FIGURE 14 and by chain lines inFIGURE 13, the end of the short arm being flattened for this purpose.This results in the rod being raised a substantial amount relatively tothe bushing 86 so as to clamp the extension 79 between the lower end ofthe bushing 86 and a rubber cushion 89 surrounding the rod 80 within thehelical spring 82 and supported by the flange 81. 'l'he cushioningeffect is, of course, assisted by the spring 82 which is compressedsufficiently to bring the cushion "89 into contact with the extension79. Moreover, the reaction due to the spring 32 and rubber cushion 89locks the platform 77 in position.

When the apparatus is portable, a cover having deep side walls isarranged to be lowered over the apparatus until the bottom edges of theside walls make contact with the base on which the apparatus is mounted,the cover subsequently being locked in position. It is then veryadvantageous to arrange the lever 83, when horizontal, to obstruct themovement of the cover to its closing position, but to permit thismovement when in the vertical position. This ensures that the apparatuscannot be covered and carried about before the motor has been madesecure.

We claim:

1. Mechanism for feeding strip material in opposite directions betweenreversible rotary members and including a rotor assembly which has asubstantial inertial resistance to acceleration and which comprises adrum over which the strip passes in travelling between the rotarymembers, said rotor assembly being rotatable freely by the stripmaterial travelling thcreover in one direction for smoothing outfluctuations in the strip movement, and means for contacting and drivingthe rotor assembly in the reverse direction at a speed such as tomaintain tension in the strip between said drum and one of said rotarymembers.

2. Mechanism according to claim 1, in which the contact between saidrotor assembly and said driving means is by friction.

3. Mechanism according to claim 2, in which said friction contact isprovided for said rotor assembly only in the reverse of said onedirection.

' 4. Mechanism according to claim 3, in which a driving wheel isprovided, said friction driving means including a freely rotatableintermediate rotary element movable to and from a position in which itis frictionally driven by said driving wheel and frictionally drivessaid rotor assembly.

5. Mechanism according to claim 4, in which the diameters of theengaging surfaces of said driving wheel, intermediate rotary element andthe rotor assembly are such as to provide a double step-up gearing.

6. Mechanism according to claim 4, in which a slide, a spring and amanually actuated snap action mechanism are provided, said rotaryelement being rotatably mounted on said slide and held in a drivingposition by said spring and positively moved away'from said position bysaid manually actuated snap action rnechanism.

7. Mechanism according to claim 6, in which the circumferential speed ofsaid drum is slightly higher than the linear speed of said stripmaterial, when said drum is being driven in the reverse direction and inwhich the reversely rotating drum maintains tension between said drumand said rotary member from which said strip is travelling.

8. Apparatus according to claim 7, in which an intermittent stripmaterial feeding means is provided, said rotary member being a sprocketarranged to receive said strip material from said intermittent stripmaterial feeding means after passing over said drum, said drum beingguidegpositions when the direction of said strip material mountedbetween said intermittent strip feeding means fwd ll rammed. and saidsprocket.

9. Apparatus according to claim 8, in which a spring Rdmnc cued m thefile of patent loaded pressure roller is provided for said drum together5 v UNIT S E NTS with a skid between said drum and said spring-loaded2,134, 45 Cobb l 25 1933 pr r ll r, said ki ing provided i h pring2,502,011 Kendall etal Mar. 23, 1950 loaded guide flanges to bearagainst opposite ends of 2,734,690 Limberger Feb. 14, 1956 said skid,additional mechanism being provided for with- 2,757,242 Ranger July 311,1956 drawing said flanges in their own planes to ineffective 102,838,305 Hoehn et al. .v. June 10, 1958

